During cardiac development, nerves grow in close anatomic proximity to blood vessels due to their need for oxygen and nutrients. Vice versa, blood vessels require closeness to nerves for tight control of vasodilation and vasoconstriction. However, their interdependence also means that malfunction of one cell type may result in dysregulation of the other. Two important sources of cardiac innervation are the parasympathetic and sympathetic nervous systems, and under- or hyper-activity of either system can lead to heart failure or arrhythmias. One common condition associated with autonomic nervous system deterioration and a predilection for cardiac arrhythmias is aging. Researchers recently demonstrated that aging-dependent vascular endothelial cell dysfunction reduces the density of neuronal axons in the heart, which in turn increases the risk of arrhythmias.

For these groundbreaking studies, researchers utilized 18-20-month-old male and female wild-type (WT) mice as the primary model of aging. Compared to young (3-month-old) mice, old mice exhibited ventricular diastolic dysfunction. Immunohistochemical staining of heart cross-sections revealed that all three major types of nerve fibers - parasympathetic, sympathetic, and sensory - were decreased in old vs. young mice. In conjunction, there was a higher incidence of inducible ventricular tachycardia in hearts isolated from old vs. young mice.

A time-course experiment revealed that nerve degeneration presented at 16 months prior to the onset of capillary rarefaction at 20 months - suggesting that nerve degeneration is not caused by loss of capillaries but rather may be due to alterations in vascular-derived neuroguidance cues. RNA sequencing (RNA-seq) of cardiac endothelial cells (ECs) isolated from old mice revealed upregulation of genes encoding pathways involved in neuronal death and axon injury, in particular semaphorin 3A (Sema3a). Interestingly, prior work had revealed that both deletion and overexpression of Sema3a can cause ventricular arrhythmias and sudden death in mutant mice. The researchers uncovered a new mechanism that involves aging ECs releasing more Sema3a, which reduces neuronal axon density in the heart, thereby promoting ventricular arrhythmias.

The most influential paradigm concerning Alzheimer's disease (AD) pathology is the amyloid cascade hypothesis and its modifications thereafter, where amyloid beta (Aβ) evolves from disordered monomers to toxic oligomers and amyloid fibrils through molecular self-assembly, modulated by environmental factors such as pH, temperature, metals, chaperones, and cell membranes. Accordingly, much effort over the past three decades has been made towards inhibiting or clearing the toxic Aβ aggregates, employing small molecules, peptidomimetics, antibodies, and, more recently, nanoparticles. A lack of clinical success, however, has shrouded these efforts, suggesting the pathophysiology of AD is multifactorial as its triggers.

Indeed, it has now been realized that, in addition to Aβ amyloidogenesis, tauopathies, apolipoprotein E, and neuroimmune activation are all causative to neurodegeneration in AD. The great (80-90%) correlation between AD subjects and patients carrying cerebral amyloid angiopathy (CAA) further suggests an important role of endothelial integrity in the development of AD pathogenesis, also evidenced by observations of cerebral endothelial dysfunction and microvascular injury induced by Aβ. Intriguingly, while Aβ originates from the proteolytic cleavage of amyloid precursor protein (APP) in endosomal membrane, deposits of Aβ are seen throughout the central nervous system, cerebral blood vessels, cerebrospinal fluid, and the plasma. Aβ-mediated vasoactivity, vascular capillary constriction, blood flow reduction, and paracellular transport have been reported with endothelial monolayers, blood-brain barrier (BBB), and biopsied human and rodent brain tissues, in connection with the production of reactive oxygen species (ROS), modified cytoskeletal network, altered tight-junction protein expression, and signaling to pericytes.

Here we show amyloid protein-induced endothelial leakiness (APEL) in human microvascular endothelial monolayers as well as in mouse cerebral vasculature. Using signaling pathway assays and discrete molecular dynamics, we revealed that the angiopathy first arose from a disruption to vascular endothelial (VE)-cadherin junctions exposed to the nanoparticulates of Aβ oligomers and seeds, preceding the earlier implicated proinflammatory and pro-oxidative stressors to endothelial leakiness. These findings were analogous to nanomaterials-induced endothelial leakiness (NanoEL), a major phenomenon in nanomedicine depicting the paracellular transport of anionic inorganic nanoparticles in the vasculature. As APEL also occurred in vitro with the oligomers and seeds of alpha synuclein, this study proposes a paradigm for elucidating the vascular permeation, systemic spread, and cross-seeding of amyloid proteins that underlie the pathogenesis of AD and Parkinson's disease.

A chronic inflammatory disease of the inner walls of blood vessels, atherosclerosis is responsible for many cardiovascular conditions. Dendritic cells, which act to recognize foreign substances in the body and mount an immune response, play an important role in the disease. They produce the signaling protein CCL17, a chemokine, which influences the activity and mobility of T cells, which track down infected cells in the body and attack the pathogens. However, CCL17 can also promote cardiovascular pathologies. People who suffer from cardiovascular diseases, or are particular susceptible to such diseases, have elevated levels of the signaling protein. In humans and mice, elevated CCL17 serum levels are associated with increased risk of atherosclerosis and inflammatory diseases of the cardiovascular and digestive systems.

"We know from our previous work that a genetic deficiency or an antibody blockade of CCL17 impedes the progress of atherosclerosis." Before now, only one signal receptor was known to contribute to the recruitment and functions of T cells. If this receptor is lacking, however, the body is not protected from the negative effects of CCL17. Mice that did not possess the receptor in question continued to have the same extent of disease driven by CCL17. If the signaling protein acted directly and exclusively on this receptor, then silencing it should have the same effects as the absence of CCL17. Consequently, there must be another signaling pathway in which CCL17 is involved, and the researchers demonstrated and described just such a pathway in the course of the new study. "We furnish clear evidence that CCL17 acts through an alternative receptor with high affinity, thereby triggering a signaling pathway that results in the suppression of anti-inflammatory, so-called regulatory T cells."

CCL17 is produced by conventional dendritic cells, signals through CCR4 on regulatory T (Treg) cells and drives atherosclerosis by suppressing Treg functions through yet undefined mechanisms. Here we show that conventional dendritic cells from CCL17-deficient mice display a pro-tolerogenic phenotype and transcriptome that is not phenocopied in mice lacking its cognate receptor CCR4. In the plasma of CCL17-deficient mice, CCL3 was the only decreased cytokine/chemokine. We found that CCL17 signaled through CCR8 as an alternate high-affinity receptor, which induced CCL3 expression and suppressed Treg functions in the absence of CCR4.

Genetic ablation of CCL3 and CCR8 in CD4+ T cells reduced CCL3 secretion, boosted FoxP3+ Treg numbers and limited atherosclerosis. Conversely, CCL3 administration exacerbated atherosclerosis and restrained Treg differentiation. In symptomatic versus asymptomatic human carotid atheroma, CCL3 expression was increased, whereas FoxP3 expression was reduced. Together, we identified a non-canonical chemokine pathway whereby CCL17 interacts with CCR8 to yield a CCL3-dependent suppression of atheroprotective Treg cells.

Development endothelial locus-1 (DEL-1) is a homeostatic protein secreted by tissue-resident cells in the gingiva and the periodontal ligament (PDL), endothelial and mesenchymal stromal/stem cells (MSCs) and some macrophage subsets, and contributes to inflammation resolution and tissue repair. Specifically, during the resolution phase of experimental periodontitis in mice, DEL-1 promotes efferocytosis and the emergence of the macrophage pro-resolving phenotype as well as stimulating alveolar bone regeneration. The pro-regenerative function of DEL-1 is largely independent of its efferocytic/pro-resolving function and involves activation of a β3 integrin-FAK-ERK1/2-RUNX2 pathway in osteoprogenitor cells. Alveolar bone regeneration fails in DEL-1-deficient mice or in mice that express a DEL-1 point mutant that cannot bind β3 integrins. The expression of DEL-1 is severely diminished in old age, both in mice and humans.

Given that DEL-1 levels decline severely in old age and mice ≥18 months of age are DEL-1 deficient, it is important to develop potential therapeutic approaches to stimulate DEL-1 expression, thereby restoring the levels of this important homeostatic protein in the elderly. We have recently shown that the macrolide antibiotic erythromycin (ERM) - but not other antibiotics, such as penicillin and josamycin - stimulates the production of DEL-1 in vascular endothelial cells. Specifically, erythromycin interacts with the growth hormone secretagogue receptor (GHSR) and activates JAK2 and p38 MAPK signaling, leading to C/EBPβ-dependent DEL-1 expression. Moreover, systemic erythromycin treatment in mice increased DEL-1 expression in the PDL, which connects the tooth to the surrounding alveolar bone. The PDL of humans and animals, including mice, contains a mostly perivascular MSC niche involved in periodontal tissue regeneration and includes progenitor cells that can differentiate into osteoblasts.

We show that erythromycin and other macrolides restore DEL-1 expression in old mice and promote regeneration of bone lost due to naturally occurring, aging-related periodontitis. The same treatment increased the bone mass in the femurs of old mice. Importantly, EM-523, a non-antibiotic derivative of erythromycin, that retains the ability to activate a homolog of the GHSR, motilin receptor, reproduced the DEL-1-dependent effect of erythromycin on bone regeneration. Mechanistically, macrolide and EM-523 treatments induced the formation of new bone by upregulating alkaline phosphatase (ALP) activity and the expression of osteogenic genes in periodontal tissue while reducing the number of osteoclasts, thereby favorably influencing the osteogenesis/osteoclastogenesis balance. Periodontal bone lost due to periodontitis has limited capacity for regeneration even after standard treatment (scaling and root planing) and surgical periodontal therapy, especially in elderly patients. Therefore, the non-antibiotic compound EM-523 may represent a safe, effective, and affordable new approach to regenerate bone lost due to periodontitis in humans and perhaps for increasing the mineral content of the skeletal bone in the elderly.

Telomeres undergo shortening with each cell division, serving as biomarkers of human aging, which is characterized by short telomeres and restricted telomerase expression in adult tissues. Contrarily, mice, featuring their longer telomeres and widespread telomerase activity, present limitations as models for understanding telomere-related human biology and diseases. To bridge this gap, we engineered a mouse strain with a humanized mTert gene, hmTert, wherein specific non-coding sequences were replaced with their human counterparts. The hmTert gene, encoding the wildtype mTert protein, was repressed in adult tissues beyond the gonads and thymus, closely resembling the regulatory pattern of the human TERT gene.

Remarkably, the hmTert gene rescued telomere dysfunction in late generations of mTert-knockout mice. Through successive intercrosses of Tert(h/-) mice, telomere length progressively declined, stabilizing below 10-kb. Tert(h/h) mice achieved a human-like average telomere length of 10-12 kb, contrasting with the 50-kb length in wildtype C57BL/6J mice. Despite shortened telomeres, Tert(h/h) mice maintained normal body weight and cell homeostasis in highly proliferative tissues. Notably, colonocyte proliferation decreased significantly in Terth/h mice during dextran sodium sulfate-induced ulcerative colitis-like pathology, suggesting limitations on cellular renewal due to short telomeres.

Our findings underscore the genetic determination of telomere homeostasis in mice by the Tert gene. These mice, exhibiting humanized telomere homeostasis, serve as a valuable model for exploring fundamental questions related to human aging and cancer.

The COcoa Supplement and Multivitamin Outcomes Study (COSMOS) is a large-scale, nationwide, randomized trial rigorously testing cocoa extract and multivitamin supplements. Two previously published studies of cognition in COSMOS suggested a positive effect for a daily multivitamin. COSMOS researchers now report the results of a third study of cognition in COSMOS, which focused on participants who underwent in-person assessments, together with the results of a combined analysis from the three separate studies.

In the in-clinic study the researchers administered detailed, in-person cognitive assessments among 573 participants in the subset of COSMOS known as COSMOS-Clinic. In their prespecified analyses of data from COSMOS-Clinic, investigators observed a modest benefit for the multivitamin, compared to placebo, on global cognition over two years. There was a statistically significant benefit of multivitamin supplementation for change in episodic memory, but not in executive function/attention. The team also conducted a meta-analysis based on the three separate studies, with non-overlapping COSMOS participants (ranging 2-3 years in treatment duration), which showed strong evidence of benefits for both global cognition and episodic memory. The authors estimate that the daily multivitamin slowed global cognitive aging by the equivalent of two years compared to placebo.

Exercise-induced hemodynamic changes lead to mechanical stress of the vascular wall, the release of circulating growth factors from the endothelium, and the release of exerkines from the exercising skeletal muscle and other organs. These three main adaptive stimuli lead to an increased activity of several molecular pathways within the vascular endothelial and smooth muscle cells, culminating in a better vasodilation and vasoconstriction responsiveness, reduced arterial stiffness, arteriogenesis, and angiogenesis, higher antioxidative capacities, and reduced oxidative stress. Recent research revealed a potential role of enhanced mitochondrial biogenesis and mitophagy, substrate metabolism, and insulin sensitivity in the vascular smooth muscle cells for exercise-induced vascular adaptations.

Some vascular adaptations, such as a favorable balance of angiogenesis and angiostasis as well as of vasodilator and vasoconstrictor responsiveness, require regular exercise, ideally throughout the entire life span. Therefore, individualization of exercise according to objective and subjective factors should be sought to achieve the best possible long-term training adherence. Repeated stimuli, at least every other day at initial stages and progressively increasing to 5-7 days per week, might be necessary to use the full potential of favorable physiological alterations, such as elevated blood pressure and improved glycemic control, which last for about 24 hours post exercise.

The cumulative volume of elevated shear stress seems more important than peak shear stress in terms of stimulating vascular remodeling. Thus, prolonged moderate-intensity workouts may be favored over shorter sessions with very high intensities, especially if injury prevention and long-term training adherence are important. High-intensity interval training may have additional benefits in the long-term, such as increased antioxidative and metabolic capacities, and thus should also be part of vascular exercise training. Resistance and aerobic exercise induce distinct macro- and microvascular adaptations; thus, both types of exercise should be implemented in comprehensive training for optimal vascular health.

Trillions of microbes live symbiotically in the host, specifically in mucosal tissues such as the gut. Recent advances in metagenomics and metabolomics have revealed that the gut microbiota plays a critical role in the regulation of host immunity and metabolism, communicating through bidirectional interactions in the microbiota-gut-brain axis (MGBA). The gut microbiota regulates both gut and systemic immunity and contributes to the neurodevelopment and behaviors of the host. With aging, the composition of the microbiota changes, and emerging studies have linked these shifts in microbial populations to age-related neurological diseases (NDs).

Preclinical studies have demonstrated that gut microbiota-targeted therapies can improve behavioral outcomes in the host by modulating microbial, metabolomic, and immunological profiles. In this review, we discuss the pathways of brain-to-gut or gut-to-brain signaling and summarize the role of gut microbiota and microbial metabolites across the lifespan and in disease. We highlight recent studies investigating 1) microbial changes with aging; 2) how aging of the maternal microbiome can affect offspring health; and 3) the contribution of the microbiome to both chronic age-related diseases (e.g., Parkinson's disease, Alzheimer's disease and cerebral amyloidosis), and acute brain injury, including ischemic stroke and traumatic brain injury.

The study of myelination in the brain is essential due to its profound impact on neural function. Myelin acts as an insulator, significantly increasing the speed and efficiency of electrical signal transmission within the nervous system, facilitating information processing and precise neuron communication. Myelination is crucial during early development and continues to influence learning, memory, and cognitive function throughout life.

Recent studies showed that the myelin of the brain changes in the life span, and demyelination contributes to the loss of brain plasticity during normal aging. Diffusion-weighted magnetic resonance imaging (dMRI) allows studying brain connectivity in vivo by mapping axons in white matter with tractography algorithms. However, dMRI does not provide insight into myelin; thus, combining tractography with myelin-sensitive maps is necessary to investigate myelin-weighted brain connectivity. Tractometry is designated for this purpose, but it suffers from some serious limitations. Our study assessed the effectiveness of the recently proposed Myelin Streamlines Decomposition (MySD) method in estimating myelin-weighted connectomes and its capacity to detect changes in myelin network architecture during the process of normal aging. This approach opens up new possibilities compared to traditional Tractometry.

Our results show that the changes occurring in myelin network architecture due to aging have critical effects on network connection strength and efficiency. Specifically, we found that efficiency and mean strength extracted from myelin-weighted connectomes reach their highest point of development around 40 years of age; after this peak, the natural degeneration of axonal microstructure begins. In the broader context of our study, which explores the overall architecture of the myelin-weighted connectome, MySD outperforms traditional Tractometry-based approaches in detecting myelin network changes during normal aging.

Immune function and redox markers are used for estimating the aging rate, namely biological age (BA). However, it is unknown if this BA and its changes can be reflected in longevity. Thus, we must quantify BA in experimental animals. In peritoneal immune cells of 202 female mice (ICR/CD1) in different ages, 10 immune and 6 redox parameters were evaluated to construct two mathematical models for BA quantification in mice by multiple linear regression. Immune and redox parameters were selected as independent variables and chronological age as dependent, developing two models: the Immunity and the Redox Clocks, reaching both an adjusted coefficient of determination of 80.9% and a standard error of 6.38 and 8.57 weeks, respectively.

Both models were validated in a different group of healthy mice obtaining a Pearson's correlation coefficient of 0.844 and 0.800 between chronological age and BA. Furthermore, they were applied to adult prematurely aging mice, which showed a higher BA than non-prematurely aging mice. Moreover, after positive and negative lifestyle interventions, mice showed a lower and higher BA, respectively, than their age-matched controls. In conclusion, the Immunity and Redox Clocks allow BA quantification in mice and both the ImmunolAge and RedoxAge in mice relate to lifespan.

Senescent cells, which accumulate in organisms over time, contribute to age-related tissue decline. Genetic ablation of senescent cells can ameliorate various age-related pathologies, including metabolic dysfunction and decreased physical fitness. While small-molecule drugs that eliminate senescent cells ('senolytics') partially replicate these phenotypes, they require continuous administration. We have developed a senolytic therapy based on chimeric antigen receptor (CAR) T cells targeting the senescence-associated protein urokinase plasminogen activator receptor (uPAR), and we previously showed these can safely eliminate senescent cells in young animals.

We now show that uPAR-positive senescent cells accumulate during aging and that they can be safely targeted with senolytic CAR T cells. Treatment with anti-uPAR CAR T cells improves exercise capacity in physiological aging, and it ameliorates metabolic dysfunction (for example, improving glucose tolerance) in aged mice and in mice on a high-fat diet. Importantly, a single administration of these senolytic CAR T cells is sufficient to achieve long-term therapeutic and preventive effects.

Cancer treatments, including chemotherapy, in addition to killing a large number of tumour cells, also result in the generation of senescent tumour cells. While senescent cells do not reproduce, they do, unfortunately, generate a favourable environment for the expansion of tumour cells that may have escaped the effects of the chemotherapy and eventually result in tumour regrowth. Researchers have described how cancer cells that have become senescent after chemotherapy activate the PD-L2 protein to protect themselves from the immune system while recruiting immune suppressor cells. The latter creates an inhibitory environment that impairs the ability of lymphocytes to kill cancer cells.

Based on these findings, scientists wondered what would be the effect of inactivating PD-L2. Interestingly, senescent cells lacking PD-L2 are rapidly eliminated by the immune system. This intercepts the capacity of senescent cells to create an immunosuppressive environment and, as a result, lymphocytes retain their full capacity to kill those cancer cells that may have escaped the effects of chemotherapy. "By blocking PD-L2 in mouse models, we have seen that chemotherapy is more effective against cancer. This finding paves the way to consider the use of a potential PD-L2 inhibitor as an adjuvant in the treatment of this disease."

Cognitive aging is the natural and gradual decline in cognitive function that occurs as people age and emerges as a major challenge for maintaining quality of life and employment. It is hence crucial to understand the neurobiology underlying cognitive aging in detail. Working memory (WM) decline is a fundamental aspect of cognitive aging and has the earliest onset among age-related cognitive deficits. Executive function is susceptible to aging. How aging impacts the circuit-level computations underlying executive function remains unclear. Using calcium imaging and optogenetic manipulation during memory-guided behavior, we show that working-memory coding and the relevant recurrent connectivity in the mouse medial prefrontal cortex (mPFC) are altered as early as middle age.

Population activity in the young adult mPFC exhibits dissociable yet overlapping patterns between tactile and auditory modalities, enabling crossmodal memory coding concurrent with modality-dependent coding. In middle age, however, crossmodal coding remarkably diminishes while modality-dependent coding persists, and both types of coding decay in advanced age. Resting-state functional connectivity, especially among memory-coding neurons, decreases already in middle age, suggesting deteriorated recurrent circuits for memory maintenance. Optogenetic inactivation reveals that the middle-aged mPFC exhibits heightened vulnerability to perturbations. These findings elucidate functional alterations of the prefrontal circuit that unfold in middle age and deteriorate further as a hallmark of cognitive aging.

CDGSH iron-sulfur domain-containing protein 2 (CISD2), a pro-longevity gene, mediates healthspan in mammals. CISD2 is down-regulated during aging. Furthermore, a persistently high level of CISD2 promotes longevity and ameliorates an age-related skin phenotype in transgenic mice. Here we translate the genetic evidence into a pharmaceutical application using a potent CISD2 activator, hesperetin, which enhances CISD2 expression in HEK001 human keratinocytes from an older person. We also treated naturally aged mice in order to study the activator's anti-aging efficacy.

We studied the biological effects of hesperetin on aging skin using, firstly, a cell-based platform, namely a HEK001 human keratinocyte cell line established from an older person. Secondly, we used a mouse model, namely old mice at 21-month old. In the latter case, we investigate the anti-aging efficacy of hesperetin on ultraviolet B (UVB)-induced photoaging and naturally aged skin. Furthermore, to identify the underlying mechanisms and potential biological pathways involved in this process we carried out transcriptomic analysis. Finally, CISD2 knockdown HEK001 keratinocytes and Cisd2 knockout mice were used to study the Cisd2-dependent effects of hesperetin on skin aging.

Four findings are pinpointed. Firstly, in human skin, CISD2 is mainly expressed in proliferating keratinocytes from the epidermal basal layer and, furthermore, CISD2 is down-regulated in the sun-exposed epidermis. Secondly, in HEK001 human keratinocytes from an older person, hesperetin enhances mitochondrial function and protects against reactive oxygen species-induced oxidative stress via increased CISD2 expression; this enhancement is CISD2-dependent. Additionally, hesperetin alleviates UVB-induced damage and suppresses matrix metalloproteinase-1 expression, the latter being a major indicator of UVB-induced damage in keratinocytes. Thirdly, transcriptomic analysis revealed that hesperetin modulates a panel of differentially expressed genes that are associated with mitochondrial function, redox homeostasis, keratinocyte function, and inflammation in order to attenuate senescence. Intriguingly, hesperetin activates two known longevity-associated regulators, namely FOXO3a and FOXM1, in order to suppress the senescence-associated secretory phenotype. Finally, in mouse skin, hesperetin enhances CISD2 expression to ameliorate UVB-induced photoaging and this occurs via a mechanism involving CISD2. Most strikingly, late-life treatment with hesperetin started at 21-month old and lasting for 5 months, is able to retard skin aging and rejuvenate naturally aged skin in mice.

Inflammaging, the characteristics of immunosenescence, is characterized by continuous chronic inflammation that could not be resolved. It not only affects older people but can also occur in young individuals, especially those suffering from chronic inflammatory conditions such as autoimmune disease, malignancy, or chronic infection. This condition led to altered immune function and as consequent immune function is reduced. Detection of immunosenescence has been done by examining the immune risk profile (IRP), which uses flow cytometry. These tests are not always available in health facilities, especially in developing countries and require fresh whole blood samples. Therefore, it is necessary to find biomarkers that can be tested using stored serum to make it easier to refer to the examination.

Here we proposed an insight for soluble biomarkers which represented immune cells activities and exhaustion, namely sCD163, sCD28, sCD80, and sCTLA-4. Those markers were reported to be elevated in chronic diseases that caused early aging and easily detected from serum samples using ELISA method, unlike IRP. Therefore, we conclude that these soluble markers are beneficial to predict the pathological condition of immunosenescence.